Crop sowing machines or seed planters for furrow sowing have been widely used during the past decades.
Usually, said machines comprise at least one rotating metering disc for retaining and administering the seeds to be planted, means to capture the seeds from a reservoir, and means to release the seeds in a controlled manner, guiding them towards furrows on the ground at a determined depth and spacing.
The rotating metering discs usually comprise orifices, holes, cradles or teeth which operate in conjunction with an air pressure difference, it being vacuum or positive pressure, for capturing and releasing the seeds. The pressure difference retains the seeds in said holes or cradles until the same is interrupted at a desired point, releasing the seeds which are then transported by conducting means towards furrows on the ground.
Commonly, sowing machines comprise a great number of sowing modules, each with its corresponding devices for opening furrows and one rotating metering disc for distributing granulates, such as seeds, into said furrows.
Traditionally, the sowing modules are driven by a single driving array which simultaneously rotates all the rotating metering discs within said modules. In cases of sowing machines with a great number of sowing modules, such as for example 20 or more, said driving array is bulky, complicated and expensive. Additionally, said driving array does not allow for individual adjustment of the rotation of each metering disk, which is necessary in those occasions in which the machine is not expected to follow a straight path and where in a curved path outer sowing modules in relation to the curve radius travel greater distances than the inner sowing modules. Said disadvantages were addressed by the use of sowing modules that utilize hydraulic and/or electric systems for driving and controlling each disk individually, as described for example in US application No 2015/334913 A1 of Gentili Jorge Alberto, published on Nov. 26, 2015.
The use of hydraulic and electric systems for driving the disks additionally allows for a more specialized control of the sowing or metering of granulates, in which the metering operation of each module can be controlled individually not only as a function of the movement or path of the sowing machine, but also as a function of data or characteristics of the soil in which the sowing is taking place, such as for example yield maps of the soil.
However, since each sowing module comprises a single metering disk, said sowing machines can only sow one type of granulate per furrow, they cannot change the granulate type during the sowing process, and require a granulate change process in order to sow another type of granulate.
Sowing machines are known in the art comprising sowing modules for double metering, also referred to as dual meters or double meters, which allow for a sowing machine to lay more than one type of seed or other granulate material, such as fertilizer, in a simultaneous, selective or alternative manner, in a single furrow or in adjacent furrows, without the need for stopping or delaying the sowing process. The selection of the type of granulate and the metering operation can be controlled as a function of the path of the sowing machine and from data of the soil such as yield maps and other relevant parameters.
In general, said double metering sowing modules comprise an individual drive and control system which allow for an on board computer of the sowing machine to control the selection of the type of seed and the metering of the same. However, double metering systems known in the art utilize complex mechanical and electronic systems for the selection and metering of the desired granulate, which are inefficient and/or present a delay between the selection of the granulate to be sowed and the effective sowing of said selected granulate. One of said double meters is described in US patent application No 2015/289441 A1 of Great Plains Manufacturing, Inc., published on Oct. 15, 2015. Said application describes a double seed metering device which comprises two metering discs, one for each type of seed, and respective seed reservoirs, and which is capable of selecting and planting seeds from two different seed types, by electronic commutation of a coaxial multiple clutch mechanism. While the device described in said application is capable of switching between seed types in an instantaneous or near-instantaneous manner, the clutch mechanism used to control the selective rotation of both discs is bulky and complex. Additionally, since the motor driving the disc is not coaxial with the same, the device requires a drivetrain to deliver power from the motor to the disc axis, which entails a loss of power, an increment in noise and more frequent and more expensive maintenance.
Another double seed metering device known in the art is the device described in US patent application No 2015/351315 A1 of CNH Industrial America LLC, published on Dec. 10, 2015. Said application describes a double seed metering device comprising two seed meters, one for each type of seed, and respective seed reservoirs, which is capable of selecting and planting seeds from between two types of different seeds, by means of the electronic commutation of clutches in the respective discs. Similarly to the application previously mentioned, the driving source is not arranged coaxially with the axis of the discs, and therefore requires a power drivetrain to drive them, which entails the disadvantages previously mentioned.
Simpler double metering devices are known in the art, as described in US patent application 2010/282144 A1 of Agro Corporation, published on Nov. 11, 2010. Said patent application describes a seed meter capable of sowing two types of seeds simultaneously, in a same furrow or in adjacent furrows. Said device comprises two coaxial metering discs, respective seed reservoirs and a driving source. While said device does not comprise a complicated clutch system and/or coupling such as the applications previously mentioned, the same is incapable of selectively activating or deactivating one or both of the discs individually.
Therefore, there is a need for double metering devices of simple design and operation, efficient, with lower power requirements and lower manufacture, maintenance and utilization costs, but which allow for total control of the manner and pacing of the sowing of more than one type of seed during operation, with instantaneous selection of the type of seed, without stopping the equipment and without manual mechanical adjustments.